Anal cancer is an emerging health crisis for homosexual men, especially within the context of human mmunodeficiency virus (HIV) infection. Like invasive cervical cancer, intra-anal cancers are largely attributable to chronic, high-risk human papillomavirus (HPV) infections. These infections and their associated low- and high-grade anal intraepithelial neoplasias (AIM) are common for men with a history of receptive anal intercourse. Though the prevalence of anal dysplasia is high, malignancy is a relatively rare occurrence. Domestically, there is no consensus for standards of care, and the outcome of treatment algorithms is largely unsatisfactory. There is an urgent need to identify key events in the underlying natural history of disease, which will enable clinicians to determine which individuals need immediate treatment or can remain under careful surveillance. More sensitive biomarkersthat can discriminate between men likely to progress from those that do not will allow better clinical algorithms to be tested. In the long term, these strategies will reduce morbidity and mortality and diminish the population's burden of disease. Methylation is an adaptive cellular process that hinders transcription of foreign DMA by making viral genomes less accessible to host-cell transcription factors and enzymes. Our recent studies suggest methylation of HPV genomes may be an epigenetic determinant, responsible for promoting latent infection and clinical disease progression. This investigation focuses on two aims using epidemiological methods and molecular biology techniques. First, we will determine whether previously observed relationships between methylation of HPV16 genomes and disease state are observable in 91 HIV/HPV16 coinfected men that have been evaluated for AIM. Second, using longitudinally-collected clinical samples and controlling for the effect of time-dependent covariates, we will determine whether particular baseline patterns of methylation in HPV16 genomes predict methylation patterns overtime in three high-risk HPVs. PUBLIC HEALTH STATEMENT: The findings from this study will improve the public's health by improving anal cancer screening accuracy through the identification of reliable biomarkers, to ultimately prevent premature death.